ABSTRACT
The status of species as a natural entity (Ruse, 1987) for biological classification has been questioned by a number of researchers. Dupre (2001) suggests that the species do not effectively function as a unit for both evolution and classification in general. He makes the point that a unit of evolution needs to be an individual, whilst a unit of classification by definition has to be of a kind. It is the individual organism that is in competition with others of its kind, as well as eking out a living from the environment. According to Dawkins (1978), the unit of evolution is the gene that provides the basic building block for evolution to occur. Organisms are merely differentiated shells surrounding genes. The interdependence of organism and gene is just one problem with this restrictive view of the basic unit of evolution. According to Dupre (2001), evolution occurs when a set of properties that characterize individuals in a phylogenetic lineage change over time. The lineage is the unit of evolution, not some entity at a single point in time. If this is the case then what properties alter and how does their alteration not change the essence of that species or gene? Both for species and genes the temporal dimension raises problems for identification and classification. The idea that a species can be the same thing throughout its evolution implies that the same species, or rather aspects of it, exists at all stages of its evolution. Such a view implies that each current species is somehow inherent in its past evolutionary lineage.
